1. Field of the Invention
The present invention is directed to a podiatric insole which forms a cushion in contact with the bottom of a user's foot. More specifically the invention is directed to a liquid-filled insole having gating means for restricting the flow of liquid from one portion of the insole to another portion of the insole.
2. Description of the Prior Art
It has long been known to provide an insole to cushion the impact of a person's foot with a supporting surface. For example, a decorative insole is disclosed in U.S. Pat. No. Des. 255,060 to Okazawa. It has also been known to provide a greater cushioning effect by forming the insole from a liquid-filled bladder which may contain water or another liquid. Liquid filled insoles are disclosed in U.S. Pat. Nos. 3,990,457, to Voorhees, 4,115,934, to Hall, and U.S. Pat. No. Des. 246,486 to Nickel. Such insoles are usually provided with individual compartments for holding liquid and the compartments do not communicate with one another.
To provide a massaging action on the bottom of a person's foot, the insole may be partially filled with a liquid, so that the liquid is free to slosh from one area of the insole to another area during movement of the foot. Such an insole is disclosed in U.S. Pat. No. 4,100,686 to Sgarlato et al. In Sgarlato et al the liquid may flow from front to back collecting at the heel or the toe.
In the Voorhees insole mentioned above, the importance was recognized of providing a liquid cushion to the load supporting surfaces of the foot; and more particularly providing individual liquid filled compartments for each of the load supporting areas. Body weight is transmitted to specific weight bearing surfaces of the foot. The weight is transmitted through the longitudinal and transverse arches to predominately three areas. These areas are the heel, the metatarsal region or the ball of the foot, and the outer border of the arch. The toes do not in themselves carry a significant portion of the total body weight.
U.S. Pat. No. 3,765,422, to Smith, discloses a fluid filled podiatric insole which is provided with flow directors for directing the flow of fluid within the insole. The directors are formed by sealing the top layer of the insole to the bottom layer of the insole. As in the Voorhees and Hall insoles, the metatarsal region of the insole is sealed off from the rest of the insole to prevent fluid from flowing from the heel portion to the metatarsal portion.